Ignition arrangement



United States Patent Otto Beesch Stuttgart-Sonnenberg, Germany 766,180

Oct. 9, 1968 Sept. 22, 1970 Robert Bosch GmbII Stuttgart, Germany Oct. 11, 1967 Germany Inventor Appl. No. Filed Patented Assignee Priority IGNITION ARRANGEMENT 4 Claims, I Drawing Fig.

US. Cl 123/169, 123/179 Int. Cl F02p 19/02 Field of Search 123/1425, 143A, 145,169IPR, I69IPRB,179A, l79B-1,

[56] References Cited UNITED STATES PATENTS 1,377,352 5/1921 Johnson 123/169(IPRB)UX 1,667,960 5/1928 Theis 123/169(IPRB)UX 1,784,541 12/1930 Rouillard l23/l69(IPRB)UX 3,089,475 5/1963 Kohler et al. 123/1425 Primary Examiner--Laurence M. Goodridge AuorneyMichael S. Striker ABSTRACT: An ignition arrangement for rotary piston en-' gines includes a spark plug arranged to ignite the fuel-air mixture of the engine. A glow plug located proximal to the spark plug for preheating the latter and the circumambient region thereof when energized. A source of electrical energy and operative connections between the latter and the spark plug and glow plugs, including a switch permitting selective energization of the glow plug alone and of the spark plug alone, both of them together or neither of them when the engine is not to be operated.

IGNITION ARRANGEMENT BACKGROUND OF THE INVENTION The present invention relates to Ignition arrangements, and more particularly to ignition arrangments for igniting the fuelair mixture in rotary piston engines.

Rotary piston engines present a particular problem with respect to the ignition of the fuel-air mixture because as a result of condensate formation, or carbon deposition or accumulations of fuel and/or oil in the trochoidal bore the development of shorts or shunts at the spark plugs is a frequent occurrence in such engines. Heretofore this has necessitated the use of complicated and accordingly expensive ignition arrangements in such engines, includinghigh-voltage condensor ignition arrangements or the use of special dual-coil ignition arrangements with two spark plugs. Aside from the fact that these arrangements are complicated, as pointed out before. and are accordingly expensive, it is a fact that at extremely low temperatures they do not operate satisfactorily.

It is therefore an object of the present invention to provide an ignition arrangement of the type in question which is not subject to these disadvantages.

A more specific object of the invention is to provide such an ignition arrangement for use with rotary piston engines and which is simple in its construction and accordingly inexpensive to manufacture and sell.

An additional object of the invention is to provide such an ignition arrangement which improves the cold-starting behavior of rotary piston engines.

SUMMARY OF THE INVENTION Pursuant to the above objects, and others which will become apparent hereafter, one feature of my invention resides in the provision of an ignition arrangement, especially for igniting the fuel-air mixture in rotary piston engines. which comprises spark plug means arranged to ignite the fuel-air mixture and electric preheating means proximal to the spark plug means and operable for preheating the latter and the circumambient region thereof. A source of electrical energy is provided and connecting means is operative for connecting the source with either or both the spark plug means and the preheating means at the will of a user.

Spark plug means for the purposes at hand are of course well known, and the source of electrical energy may be the conventional battery employed for energizing such spark plug means. As far as the preheating means is concerned, this may be of any known suitable construction, for instance a glow plug or another heating element which preheats the spark plug and the circumambient region of the spark plug so that ignition will take place after only a few seconds even at extremely low temperatures. As the rotation of the engine piston increases, a smooth operation is guaranteed. Furthermore, my novel ignition arrangement eliminates shunting or shorting of the spark plug and the objectionable oil carbon or oil depositlOnS.

As the number of rotations per minute or the load on the rotary piston engine increases, it is necessary that the moment of ignition of the fuel-air mixture be precisely controlled. This is accomplished in known manner by the conventional coil ignition system known from Otto-engines, that is the type of ignition system in which the moment of ignition is determined by a primary-current interrupter controlled by an ignition cam. As soon as this ignition system is capable of performing its assigned function the preheating means may be de-energized because it will no longer be needed.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself. however, both as to its construction and its method of operation. together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING The single figure is a diagram illustrating one example of an ignition system according to the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS As illustrated in the drawing, a conventional rotary piston engine of known construction is identified with reference numeral l. Therotary piston is not shown because it is not essential for an understanding of the invention. ln.known manner a spark plug 2 is associated with the rotarypiston engine 1. Proximal to the spark plug 2 there is provided a preheating means, here illustrated diagrammatically as a conventional glow plug 3 although another suitable heating element may be substituted. The glow plug 3 or analogous heating means is located close enough to the spark plug 2 so that the latter and the circumambient region of the spark plug 2 ill be subjected to heating when the glow plug is energized. The position of the glow plug 3 with respect to the spark plug 2 is determined only by the consideration of effective heating of the latter and the circumambient region thereof; as far as the direction of rotation of the rotary piston of the rotary piston engine I is concerned, the location of the glow plug 3 is immaterial. In other words, it is immaterial whether the glow plug 3 is located upstream of or downstream of the spark plug 2 as seen with respect to the direction of rotation of the rotary piston.

A conventional starter battery is identified with reference numeral 6, a conventional starter with reference numeral 7 and the interrupter 8 and ignition coil 9 are conventional and are know from ignition coil systems used in conjunction with automobile engines. Electrical conductors l0 connect the spark plug 2 with the ignition coil 9, the interrupter'8 and. ignition switch 4, the glow plug 3 with the ignition switch 4, and the starter 7 with the ignition switch 4. A further conductor 10 connects the ignition switch 4 with the starter battery 6. The ignition switch 4 is of the multi-position type and comprises in the illustrated embodiment a rotary contact 5 which can be moved between positions identified in the drawing with reference designations O. R. H and S. The designation 0 stands for off." the designation R stands for running." the designation H stands for heating and S stands for start".

The operation of the arrangement will be obvious from what has been said before and from a consideration of the drawing. To start the rotary piston engine 1 the rotary contact-5 of the ignition switch 4 is of the multi-position type and comprises in ready well known-is turned from position 0 to the position H. This establishes a circuit connection between the starting battery 6 and the glow plug 3, energizing the same. The rotary contact 5 is maintained in the position .H for a requisite period of time, for example approximately one minute, during which the glow plug 3 or analogous heating element is heatedand in turn heats the spark plug 2 and the circumambient region thereof. Subsequently, the contact 5 is turned to position 5 in which the glow plug 3 remains energized while additionally the spark plug 2 is electrically connected with the starter battery 6. In this position the rotary piston engine 1 will start reliably and rapidly even at extremely low ambient temperatures, owing to the preheating of the spark plug 2 and the fuel air mixture in the circumambient region of the spark plug 2.

As soon as the engine 1 is started the contact 5 of the ignition switch 4 is moved to the position R, thereby disconnecting the glow plug 3 from the starter battery 6 while leaving the spark plug 2 connected with the battery 6. Evidently. at this point the glow plug is no longer required for operation of the engine I.

In the event that the engine 1 does not run smoothly and properly upon starting, ignition of the fuel-air mixture by the spark plug 2 may be temporarily facilitated by leaving the glow plug 3 energized until such time as the engine will run smoothly. This is accomplished by leaving the contact 5 of the ignition switch 4 in the position H until the engine runs smoothly, at which time the contact 5 is then turned in conventional manner to the position R.

It will be evident that various modifications of the exemplary embodiment illustrated in the drawing are possible without departing in any way from the scope and concept of the invention. Clearly, as far as elements are concerned which are already known in this art, a description of these elements is not necessary.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.

lclaim:

1. An ignition arrangement for igniting the fuel-air mixture in rotary piston engines, comprising a first electric ignition circuit including a glow plug for preheating and igniting said fuelair mixture when the rotary piston engine is cold; a second further comprising a source of electrical energy connectable with said first and second electric ignition circuit, respectively.

3. An ignition arrangement as defined in claim I, said glow plug being arranged proximal to said spark plug.

4. An ignition arrangement as defined in claim 1, wherein said switch means is operative for selectively energizing both of said ignition circuits when said engine is cold. and only said second ignition circuit when said engine is warm. 

